AN ECONOMIC MODEL FOR IRRIGATION WELL MANAGEMENT IN A DECLINING AQUIFER

A computerized model is developed that uses the aquifer characteristics and irrigation requirements to estimate hydraulic properties of a well pumping from an unconfined aquifer with a steadily declining water table. The model simulates electrically-powered well operation under the most economical conditions. High versatility of model inputs allows examination of many facets of well management. One example is the effect of electricity price on the ratio of energy cost of total cost of supplying water at different average total heads. At current electricity prices, energy accounted for 65 to 70 percent of total water costs. In a second example, as average annual efficiency decreased, average annual cost per acre-foot increased and average annual pumping volume decreased, leaving average annual total energy costs almost constant.